Alloy



an at 252% COLIN G. FINK, OF EAST ORANGE, NEW JERSEY, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

Patented June 8, 11920.

ALLOY.

1,342,993, Specification of Letters Patent.

No Drawing. Application filed November 22, 1915.

New Jersey, have invented certain new and useful Improvements in Alloys, of which the following is a specification.

The present invention in one of its aspects relates to a new alloy comprising essentially nickel and cobalt and preferably containing also several per cent. of manganese.

Heretofore such alloys of nickel and cobalt as have been prepared have been brittle and non-ductile at ordinary temperatures. This was due in accordance with my experiments to the presence of carbon in the alloy. The alloy prepared in accordance with my invention is free from carbon and is-exceedingly ductile, malleable and pliable at ordinary temperatures.

I find that this new allow has a relatively low heat conductivity. This property besides various others, such, for example, as high melting point, slight tendency to vaporize or spatter electrically, inoxidizability, good electrical conductivity and weldability render the alloy particularly suitable for the'support of incandescent filaments in electric lamps where the cooling elfect of the supports or terminals has a great influence on the efficiency of the lamp.

The percentage of cobalt and nickel may be varied, but I find about 20to 30 parts by Weight of cobalt and 80 to 70 parts by- Weight of nickel to be preferable for most purposes. These metals are melted together in an alundum crucible, the crucible being preferably surrounded by a hydrogen atmosphere. An electric furnace of the type described in Coolidge Patent No. 1,096,414, having a tungsten resistor, or any other suitable furnace having a carbon-free atmosphere may be used. When these metals are melted, several per cent. of manganese is preferably added. The manganese content may vary from about one to ten parts. With high percentages of cobalt, the manganese content should be proportionately high. For most'purposes I find about two parts of manganese are preferable.

In preparing the alloy care should be taken to avoid aluminum, silicon, calcium and other basic impurities. The alloying materials should also be free from sulfur,

Serial No. 62,713.

phosphorus andcarbon. The latter impurities may be removed by prolonged heating in hydrogen at about 800 to 900 (1., or higher. Carbon monoxid or dioxid or hydrocarbon vapors should be excluded from the protective atmosphere in which the refining treatment is carried out. The above impurities tend to make the alloy brittle but traces of iron or copper do not appear to have a detrimental effect.

In case the metals to be alloyed contain basic impurities, the melt is maintained for about one hour at a temperature of about 1700 (1, which is above the melting point of cobalt. By this refining treatment various impurities are slagged off. For example, aluminum, magnesium, calcium and silicon, rise to the surface of the melt as exids or complex compounds. The metalthen is cooled to about 1250 C. and is then taken out of the mold and chilled in water. Chilling develops a fine crystalline structure and separates the slag from the metal.

The alloy is exceedingly ductile and malleable and may readily be drawn into wire. It may be rolled from directly down to .02 without any intermediate anneal. The alloy is almost pure white in luster, being a blend between the yellowish tint of nickel and the bluish tint of cobalt.

Cobalt-nickel has an exceptionally low heat conductivity and does not absorb gas and is therefore particularly suitable as a supporting or current lead wire for electric incandescent lamps. As the melting point of the alloy is above 1500 C. and the metal is non-spattering, wires of unusually small diameter maybe used as a current lead wire in an electric lamp. The wire may become red hot during the operation of the lamp without the envelop of the lamp being discolored. By the use of fine current lead wires consisting of the-new alloy the efficiency of low voltage miniature lamps is very much improved because the heat loss by conduction from the filament is mate-v rially reduced.

What I claim as new and desire to secure by Letters Patent of the United States, is,

1. A ductile alloy consisting mostly of nickel and containing at least 20% cobalt and free from carbon, sulfur, phosphorus and basics-impurities.

2. A Wire for incandescent lamp and other uses, comprising by weight about 20 to 30 nickel and containing at least 20% cobalt with a small proportion of manganese and 10 free from basic elements and from carbon, sulfur and phosphorus.

In Witness whereof, I have hereunto set my hand this 19th day of November, 1915.

COLIN G. FINK. 

